At present, there are widely used in the art of weaving such mechanisms which have a reed formed by a plurality of toothed discs, the discs being successively mounted on a shaft in an angularly staggered fashion, so that their teeth and valleys define helical surfaces of the same pitch.
To prevent sagging and vibration of the discs, underlying them are support or back-up rollers engaging the apices of the teeth of the discs.
However, this mode of engagement between the support rollers and the teeth of the discs more often than not results in deformation of the teeth, which affects the quality of the beating-up of the weft threads, and, ultimately, affects the quality of the cloth being woven.
Such deformation of the teeth of the discs can be precluded by having the support rollers with helical lugs defining a helical surface engaging the helical surface defined by the valleys of the discs and having a pitch equalling that of the helical surface defined by the teeth of the discs. Then, in order to provide for proper cloth formation, i.e., for the desired pattern of the motion of the discs of the reed, the support rollers are to be rotated in synchronism with the shaft of the discs, by an individual drive.
However, the incorporation of such a drive complicates the structure of the weaving mechanism. Moreover, in mechanisms of this kind, there is an eventuality of the support rollers slipping relative to the teeth of the discs, should the driving chain of the drive be somehow impaired, which affests the synchronism in the rotation of the shaft of the discs and of the support rollers, with the eventual breakdown of the discs. This, in turn, cannot but affect the quality of the cloth being woven.